Packet filters may evaluate or analyze “packets” which may be transferred between one or more computing devices that are in communication with each other, for example via the Internet and/or via wireless communication.
An Internet Protocol (IP) router may permit or may block the flow of various types of IP packets via IP packet filtering. Packet filtering can be applied to incoming and outgoing IP flow traffic. Input packet filters may define what inbound IP traffic may be allowed to be accepted on one or more interfaces. Output packet filters may define what IP traffic may be sent from one or more interfaces.
Packet filtering tools may be available in different operating systems (OSs), such as but not limited to “Netfilter” on Linux and Windows; “WinpkFilter” on Windows; and “LittleSwitch” on Apple's OS, for example.